A number of heterocyclic sulfenamides, thiols and disulfides have been well known, as has been their use in the vulcanization of rubber. The best known and most widely used are based on benzothiazole. Thus, the benzothiazole sullenamides, such as N-t-butyl-2-benzothiazole sulfenamide (TBBS) and N-cyclohexyl-2-benzothiazole sulfenamide (CBS) have become standard accelerators of vulcanization. Similarly, the thiol derivative, 2-mercaptobenzothiazole (MBT) and the disulfide derivative, 2,2'-benzothiazole disulfide (MBTS), are standards of the industry.
To a lesser degree, other N-heterocycles have been suggested as the basis for sulfenamides. For example, British Patent 795,174 describes a process for making a large variety of sulfonamide compounds for use as diuretics and antibacterial agents in which the sulfenamide equivalent is first made as an intermediate. Twenty-six different basic heterocycles are suggested, and a wide variety of substituents and fused ring variations are included, as well.
Similarly, British Patent 1,342,046 discloses a process for making heterocyclic sulfenamides, based on diazine, triazine and pyridine thiols, encompassing an unlimited number of possible compounds, suggested to be effective vulcanization accelerators for rubber.